name - (Required, ForceNew)Two topics on a single account in the same region cannot have the same name. A topic name must start with an English letter or a digit, and can contain English letters, digits, and hyphens, with the length not exceeding 256 characters.

maximum_message_size - (Optional)This indicates the maximum length, in bytes, of any message body sent to the topic. Valid value range: 1024-65536, i.e., 1K to 64K. Default value to 65536.